For some reason, we have sheets of foam in our shed and I had Gorilla glue, so decided to put them to debatedly good use. I cut one piece of foam to fit the very bottom edge and then another one to fit the bottom grill. That was half an inch too small, so I bought half-inch foam and I was barely able to reattach the ABS using the original holes, although the top edge somehow now fits much closer to the bumper. I tried shrinking it with my heat ray on low yesterday and it did not do any good. I held a 2x4 against it, which prevented it from sagging, but I thought that the only way to make it work was to press a thin strip of metal against it and heat that.
You can see how wide the pieces are and the left edge of the dam was misshapen from lying on the ground. I am going to fit pieces for the edges.
Would resin attach the foam to the plastic well or should I use something else? I could definitely fiberglass the foam, although I would need to sand it down first, and I doubt that would be easy to do evenly.